1. Field of the Invention
The present invention relates to a filtering device comprising a water suction case having a plurality of water suction ports connected to water flow passages formed therein so as to make gravel spreaded over the bottom of a water basin perform the filtering operation, the case being buried in the gravel to be disposed, and a pumping means connected to the water suction case so as to circulate water in the passage to the upper portion of the water basin.
2. Description of the Prior Art
Such conventional filtering devices are generally used as so-called bottom type filtering devices using gravel as a filtering material, and a plurality of water suction ports are heretofore perforated at the upper surface of the water suction case of flat box shape (e.g., Japanese Patent Laid-open No. 172322/1985).
However, when burying the water suction case in the gravel in the above-mentioned conventional filtering device, it is difficult to do so under the state that the gravel has already been spreaded over the bottom of a water basin. Therefore, it is necessary to gravel from above the water suction case which is mounted in the state that the gravel is removed. Further, since the water suction port is directly covered with the gravel, the suction port is feasibly clogged up.